Hyperthermia treatment advances for brain tumors

Abstract

Hyperthermia therapy (HT) of cancer is a well-known treatment approach. With the advent of new technologies, HT approaches are now important for the treatment of brain tumors. We review current clinical applications of HT in neuro-oncology and ongoing preclinical research aiming to advance HT approaches to clinical practice. Laser interstitial thermal therapy (LITT) is currently the most widely utilized thermal ablation approach in clinical practice mainly for the treatment of recurrent or deep-seated tumors in the brain. Magnetic hyperthermia therapy (MHT), which relies on the use of magnetic nanoparticles (MNPs) and alternating magnetic fields (AMFs), is a new quite promising HT treatment approach for brain tumors. Initial MHT clinical studies in combination with fractionated radiation therapy (RT) in patients have been completed in Europe with encouraging results. Another combination treatment with HT that warrants further investigation is immunotherapy. HT approaches for brain tumors will continue to a play an important role in neuro-oncology.

Keywords: Brain tumor; hyperthermia therapy; laser interstitial thermal therapy; magnetic hyperthermia therapy; photothermal therapy.

Figure 1.

Brain tumor illustration demonstrating Laser Interstitial Thermal Therapy (LITT). A) Schematic representation of intratumoral placement of laser catheter and brain tumor ablation. B) Schematic representation of brain tumor ablation demonstrating post-LITT contrast enhancement consistent with LITT related blood brain barrier (BBB) disruption and LITT related perifocal edema.

Figure 2.

Schematic representation of Magnetic hyperthermia therapy in the brain. A) Alternating magnetic field is applied to the patient after local administration of magnetic nanoparticles (black spheres), generating highly localized hyperthermia. B) Heat is produced via hysteresis losses and Brownian relaxation (a process in which frictional heating is generated by the physical rotation of the magnetic particle)

Figure 3.

Illustration of brain tumor Nanoparticle-mediated Photothermal Therapy (PTT) A) Schematic representation of local NIR light application to a brain tumor after photothermal agents (PTAs) administration (black spheres). B) Schematic illustration demonstrating NIR light excitation of PTAs within the brain tumor. PTAs absorb NIR light and emit thermal energy acting as local heat sources.

Figure 4.

Schematic illustration summarizing some of the less common HT modalities that have been employed for brain tumor treatment. HT for brain tumors has been performed with ultrasound (US), radiofrequency (RF) and microwaves (MW)